Poylmeric composition for use as a temporary support material in extrusion based additive manufacturing

ABSTRACT

The polymeric composition of this invention can be used as a temporary support material in the additive manufacturing of three dimensional articles without compromising the quality of the ultimate product, reducing printing speed, increasing cost, increasing the incidence of printer jamming, or requiring printers of increased complexity. This invention more specifically discloses a polymeric composition which is particularly useful as a temporary support material for utilization in three-dimensional printing, said polymeric composition being comprised of a first polymeric component which is suitable for use as a modeling material and a second polymeric component which is immiscible with the first polymeric component, wherein the polymeric composition has a continuous phase, wherein the continuous phase is comprised of the second polymeric component, and wherein the polymeric composition has a Shore A hardness of at least 80.

This is a divisional of U.S. patent application Ser. No. 16/709,364,filed on Dec. 10, 2019, which is a divisional of U.S. patent applicationSer. No. 14/848,526, filed on Sep. 9, 2015, which claims the benefit ofU.S. Provisional Patent Application Ser. No. 62/047,723, filed on Sep.9, 2014. The teachings of U.S. patent application Ser. No. 16/709,364,U.S. patent application Ser. No. 14/848,526 and U.S. Provisional PatentApplication Ser. No. 62/047,723 are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

By definition, “rapid prototyping” is a group of techniques that can beused to quickly fabricate a scale model of a physical part or assemblyusing 3-dimensional computer aided design (CAD) data. In rapidprototyping, construction of the part or assembly is usually done in anadditive, layer-by-layer fashion. Those techniques that involvefabricating parts or assemblies in an additive or layer-by-layer fashionare termed “additive manufacturing” (AM), as opposed to traditionalmanufacturing methods which are mostly reductive in nature. Additivemanufacturing is commonly referred to by the general public as “3Dprinting”.

According to ASTM Committee F42 on Additive Manufacturing Technologies,there are currently seven basic AM technologies: material extrusion,material jetting, binder jetting, vat photopolymerization, sheetlamination, powder bed fusion and directed energy deposition. The mostwidely used of these seven AM technologies is based on materialextrusion. While some variations exist, this technology generallyinvolves feeding a thermoplastic polymer in the form of a continuousfilament into a heated nozzle, where the thermoplastic filament becomesa viscous melt and can be therefore extruded. The 3-dimensional motionof the nozzle or the extruder assembly is precisely controlled by stepmotors and computer aided manufacturing (CAM) software. The first layerof the object is deposited on a build substrate, whereas additionallayers are sequentially deposited and fused (or partially fused) to theprevious layer by solidification due to a drop in temperature. Theprocess continues until a 3-dimensional part is fully constructed. Theprocess may also involve a temporary support material that providessupport to the part being built and is subsequently removed from thefinished part by mechanical means or dissolution in a suitable liquidmedium. This process is commonly referred to as fused depositionmodeling (FDM) or fused filament fabrication (FFF). This technology wasfirst described by the teachings of U.S. Pat. No. 5,121,329.

U.S. Pat. No. 5,121,329 more specifically discloses an apparatus formaking three-dimensional physical objects of a predetermined shape bysequentially depositing multiple layers of solidifying material on abase member in a desired pattern, comprising: a movable head havingflow-passage means therein connected to a dispensing outlet at one endthereof, said outlet comprising a tip with a discharge orifice ofpredetermined size therein; a supply of material which solidifies at apredetermined temperature, and means for introducing said material in afluid state into said flow-passage means; a base member disposed inclose, working proximity to said dispensing outlet of said dispensinghead; a mechanical means for moving said dispensing head and said basemember relative to each other in three dimensions along “X,” “Y,” and“Z” axes in a rectangular coordinate system in a predetermined sequenceand pattern and for displacing said dispensing head a predeterminedincremental distance relative to the base member and thence relative toeach successive layer deposited prior to the commencement of theformation of each successive layer to form multiple layers of saidmaterial of predetermined thickness which build up on each othersequentially as they solidify after discharge from said orifice; and ameans for metering the discharge of said material in a fluid stream fromsaid discharge orifice at a predetermined rate onto said base member toform a three-dimensional object as said dispensing head and base memberare moved relative to each other. In one embodiment of the inventiondescribed in this patent, the material is in the form of a continuousflexible strand.

Material extrusion based AM (FDM or FFF) has become quite popular overthe course of the past decade, largely due to the emergence of low-cost,desktop 3D printers. Such printers feature small sizes (similar todesktop inkjet printers) and are usually sold at a price of under $5,000(United States dollars) per unit. Examples of material extrusion baseddesktop 3D printers are Replicator® series 3D printers from MakerBotIndustries, H-series printers from Afinia, M-series printers fromMakerGear LLC, etc. Some of those 3D printers are based on open-sourcehardware and are available as do-it-yourself kits.

There are several thermoplastic polymers that are currently being usedin material extrusion based AM processes, such as FDM or FFF. Thosematerials include acrylonitril-butadiene-styrene (ABS), poly(lacticacid) (PLA), polycarbonate (PC), polystyrene (PS), high impactpolystyrene (HIPS), polycaprolactone (PCL), and polyamide as well assome other polymeric materials. However the most commonly used materialsare ABS and PLA.

ABS has the advantage of good overall mechanical properties; however itsuffers from relatively large volumetric shrinkage and the generation ofunpleasant odors. Furthermore, the generation of potentially toxicdegradation products during printing makes ABS a less suitable optionfor desktop 3D printers because such printers generally do not have aheated build envelope and an effective mechanism to eliminate the odorand toxic degradation products. PLA, on the other hand, has lessvolumetric shrinkage which allows it to be printed properly even withouta heated build envelope. It generates no unpleasant odor duringprinting, and the main degradation product is lactic acid which posesminimal health risk to 3D printer users. According to many surveys, PLAis increasingly becoming the most used material for desktop 3D printers.However, PLA still suffers from a number of drawbacks, including poorimpact strength and a low softening temperature. The low softeningtemperature leads to difficulties with extrusion and printing quality.

A schematic of a typical printer head or extruder used on a FDM/FFF 3Dprinter is illustrated in FIG. 1 . During conventional use a filament 1with an average diameter of d_(F) is moved by two counter-rotating feedrollers 2, subsequently into a filament barrel 3 with an inner diameterof d_(I) and a heater block 4. To function properly, the filament shouldremain solid in the filament barrel and only becomes a viscous melt inor close to the heater block section. The solid part of filament 1 inthe filament barrel 3 functions as a plunger that pushes the melt out ofthe nozzle 5. The nozzle orifice usually has a diameter in the range of0.2 mm to 0.5 mm, more typically has an orifice diameter which is withinthe range of 0.3 mm to 0.4 mm.

As mentioned earlier, in FDM/FFF processes a temporary support materialis required in some cases to make a model of a desired shape. Thefunction of the support material is to provide a temporary mechanicalsupport for overhanging portions of the model that are not directlysupported by the modeling material in lower layers of the model. Inother words, the temporary support material provides a base onto whichthe molten modeling material can be applied. After the extrusion hasbeen completed the temporary support material is then be removed toprovide the model of the size and dimensions which are desired.Currently three different types of support materials are being used inFDM/FFF processes. These materials include (1) the modeling material,(2) a water-soluble material, and (3) a solvent soluble material.

In some cases, the modeling material used in making the body of themodel can be utilized as the temporary support material. In other words,the temporary support material is the same polymeric composition as isused in making the body of the object being made. For instance, this maybe the only choice for FDM/FFF 3D printers which are equipped with onlyone extruder or printing head. However removing the temporary supportstructure in such cases can be very challenging because the adhesionbetween the support structure and the model is often too strong. In anycase, removing the temporary support structure requires extensive laborand can often lead to poor surface appearance and even mechanical damageto the part being made.

Water-soluble thermoplastic materials which can be used as the temporarysupport material are subsequently removed by dissolving then in water orwater-based solutions. Poly(vinyl alcohol) is a good example of awater-soluble polymeric materials that can be used as a temporarysupport. Additional examples of water-soluble polymeric materials whichcan be used as a temporary supports are described in U.S. Pat. No.7,754,807 B2. These polymers contain carboxylic acid groups and aresoluble in alkaline solutions. However, a significant drawbackassociated with utilizing of this class of temporary support materialsis the difficulty to preserve them because they typically absorb largeamounts of moisture from the atmosphere. The absorbed water can thenchange the physical dimension of the material (usually used in afilament form) as well as its thermal and rheological properties whichcan lead to printing problems, such as incorrect feeding and evenprinter jam. Accordingly, support materials in this class often haverelatively short shelf lives and need to be used quickly once thematerial is opened from the packaging and exposed to the air.

Thermoplastic materials which are soluble in organic solvents can beused as the temporary support material and can be removed from the partbeing made by dissolving them in an organic solvent. The solvent ischosen so that only the support material is dissolved without dissolvingthe modeling material. In other words, the temporary support materialshould be soluble in the solvent chosen, but the modeling materialshould not be soluble in the solvent. One example of solvent-solublesupport materials is high impact polystyrene (HIPS) which can be removedwith limonene as the organic solvent. This approach however has severaldrawbacks. First, relatively large amounts of organic solvents aretypically required to remove the support structure, leading to addedcost and handling difficulties. Some organic solvents which canpotentially be used are flammable, toxic to humans and animals, and/orhave an adverse effect on the environment. Finally, the solvent waste(with support material dissolved in it) may require special disposal,which further leads to added cost, complexity, and environmental impact.

There is currently a need for a better temporary support material forFDM/FFF processes. It is important for such a material to provideadequately support the overhanging portions of the part beingmanufactured. It should be capable of being easily removed withoutdamaging the part or part surfaces in contact with the supportstructure. Removal of the support structure should not require extensivelabor or the use of undesirable organic or aqueous solutions. Thetemporary support material should also offer a reasonably long shelflife. Finally, these objectives should be realized without compromisingthe quality of the ultimate product, reducing the speed of printing,increasing cost, or increasing the complexity of the printer.

SUMMARY OF THE INVENTION

This invention provides a polymeric composition which offer an array ofproperties which make it highly desirable of use as a temporary supportmaterial in three-dimensional printing. The support material of thisinvention can be used to generate support structures that can be easilyremoved by simple mechanical means. In other words, removal of thetemporary support material can be done in a reasonably short amount oftime and accordingly takes less labor. It can be utilized advantageouslyin manufacturing most 3D printed parts and can be used in mostconventional FDM/FFF 3D printers. The material does not absorb anytangible amount of water (i.e. less than 1 weight percent and preferablyless than 0.5 weight percent) and accordingly offers a long shelf-lifebefore being used. It does not rely upon any potentially dangerous,odorous, toxic, or flammable organic liquid or aqueous solvents.Finally, the polymeric composition of this invention can be used in theadditive manufacturing of three dimensional articles withoutcompromising the quality of the ultimate product, reducing printingspeed, increasing cost, increasing the incidence of printer jamming, orrequiring printers of increased complexity.

This invention more specifically discloses a polymeric composition whichis particularly useful as a temporary support material for utilizationin three-dimensional printing, said polymeric composition beingcomprised of a first polymeric component which is suitable for use as amodeling material and a second polymeric component which is immisciblewith the first polymeric component, wherein the polymeric compositionhas a continuous phase which is comprised of the second polymericcomponent, and wherein the polymeric composition has a Shore A hardnessof at least 80. In most cases the polymeric composition will also have adiscontinuous phase which is comprised of the first polymeric component.However, it is possible for the polymeric composition to be of aco-continuous morphology wherein both the first polymeric component andthe second polymeric component are present in a continuous phase.

The present invention explicitly reveals a polymeric composition whichis particularly useful as a temporary support material for utilizationin three-dimensional printing, said polymeric composition beingcomprised of a first polymeric component which is suitable for use as amodeling material and a second polymeric component which is immisciblewith the first polymeric component, wherein the polymeric compositionhas a continuous phase and a discontinuous phase, wherein the continuousphase is comprised of the second polymeric component, wherein thediscontinuous phase is comprised of the first polymeric component, andwherein the polymeric composition has a Shore A hardness of at least 80.

The subject invention further reveals a filament for use inthree-dimensional printing as a temporary support material, saidfilament having a diameter which is within the range of 1.65 mm to 1.85mm, wherein said filament is comprised of a polymeric compositioncomprising a first polymeric component which is suitable for use as amodeling material and a second polymeric component which is immisciblewith the first polymeric component, wherein the polymeric compositionhas a continuous phase, wherein the continuous phase is comprised of thesecond polymeric component, and wherein the polymeric composition has aShore A hardness of at least 80. In most cases the polymeric compositionwill also include a discontinuous phase which is comprised of the firstpolymeric component.

The present invention also discloses a filament for use inthree-dimensional printing as a temporary support material, saidfilament having a diameter which is within the range of 2.75 mm to 3.15mm, wherein said filament is comprised of a polymeric compositioncomprising a first polymeric component which is suitable for use as amodeling material and a second polymeric component which is immisciblewith the first polymeric component, wherein the polymeric compositionhas a continuous phase, wherein the continuous phase is comprised of thesecond polymeric component, and wherein the polymeric composition has aShore A hardness of at least 80. In most cases the polymeric compositionwill also include a discontinuous phase which is comprised of the firstpolymeric component.

The subject invention further reveals in the process of manufacturing athree-dimensional article by additive manufacturing which includesextruding at least one filament of a modeling material and at least onefilament of a temporary support material into a desired geometric shape,the improvement which comprises the temporary support material being apolymeric composition which includes a first polymeric component whichis suitable for use as the modeling material and a second polymericcomponent which is immiscible with the first polymeric component,wherein the polymeric composition has a continuous phase, wherein thecontinuous phase is comprised of the second polymeric component, andwherein the polymeric composition has a Shore A hardness of at least 80.In most cases the polymeric composition will also include adiscontinuous phase which is comprised of the first polymeric component.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration showing a typical printer head or extruder asis used in additive manufacturing printers.

FIG. 2 is a schematic illustration showing the manner in which printingheads can extrude a modeling material onto a support material in makinga desired part.

FIG. 3 is an illustration showing a support/model interface, amodel/model interface, and a support/support interface betweenrespective layers of material used in manufacturing a desired part.

FIG. 4 is an illustration showing the removal of support material frommodel material at the interface between the support material and themodel material.

DETAILED DESCRIPTION OF THE INVENTION

The new temporary support material utilizes an immiscible polymer blendthat is composed of at least two polymeric components. The firstpolymeric component (“component A”) has good adhesion with the modelingmaterial, and is preferred to be the modeling material itself. Thesecond polymeric component (“component B”) exhibits poor adhesion withthe modeling material, and is immiscible with the component A. It isalso preferred that the component A forms the minor phase (i.e.discontinuous phase rather than the continuous phase) in the polymerblend.

In the temporary support material of this invention the first polymericcomponent is normally present at a level which is within the range ofabout 10 weight percent to about 45 weight percent with the secondpolymeric component being present in the polymeric composition at alevel which is within the range of about 55 weight percent to about 90weight percent. In such polymeric compositions the first polymericcomponent will typically be present at a level which is within the rangeof about 15 weight percent to about 40 weight percent with the secondpolymeric component being present at a level which is within the rangeof about 60 weight percent to about 85 weight percent. It is frequentlypreferable for the first polymeric component to be present in thepolymeric composition at a level which is within the range of about 20weight percent to about 30 weight percent and for the second polymericcomponent to be present in the polymeric composition at a level which iswithin the range of about 70 weight percent to about 80 weight percent.

In order to provide adequate support to the part being built, thesupport material is required to have reasonable stiffness. The Shore Ahardness of the support material should be no less than 80, typically atleast 85, more typically at least 90, and preferably at least 95 (ShoreA) or higher.

The support material also needs to have enough adhesion to the modelingmaterial to allow for that the latter can be printed reliably on thesupport structure generated by the support material. However theadhesion should not be too strong as to render removal of the supportdifficult. The importance of adhesion is further illustrated in FIGS.2-4 .

As is illustrated in FIG. 2 , printing head 11 extrudes modelingmaterial 13 and extruder head 12 extrudes support material 14. As can beseen in FIG. 3 , the model material 13 can be extruded onto the supportmaterial 14 with a resulting support/model interface, model material 13can be extruded onto model material 13 with a resulting model/modelinterface, support material 14 can be extruded onto support material 14with a resulting support/support interface, or support material 14 canbe extruded onto model material 13 with a resulting support/modelinterface.

When the support material is removed mechanically from the modelmaterial interfaces need to be considered: support-model interface,model-model interface, and support-support interface. The relativestrength (or weakness) of the 3 types of interfaces as illustrated inFIG. 3 determine where the fracture occurs when trying to remove thesupport. In other words, the fracture can occur at the support-modelinterface, the model-model interface, or the support-support interface.When fracture occurs at the model-model interface, the printed part isdamaged. When fracture occurs at the support-support interface, it wouldresult in incomplete support removal, leaving residual support materialon the model and compromising the surface appearance of the model.Therefore the ideal situation is that the fracture occurs at thesupport-model interface, as shown in FIG. 4 . One of the key objectivesof this invention is to provide a support material that, when usedproperly, always leads to fracture at the support-model interface. Thisrequires the strength of the support-support interface and themodel-model interface to be significantly stronger than themodel-support interface.

This invention discloses a facile method to produce such supportmaterials. The method involves the preparation of a polymer blend thatis composed of at least two components, component A and B. The polymerblend needs to meet the following criteria:

-   1. Component A exhibits good adhesion to the modeling material, and    is preferably the modeling material itself;-   2. Component B exhibits poor adhesion to the modeling material-   3. The blend has a phase separated morphology, whereas the    continuous phase is composed of primarily component B.

In addition, the support material is preferably to exhibit reasonablestiffness, so that it can withstand the stresses during the 3D printingprocess. Our experience suggests that the hardness of the supportmaterial is preferred to be 95 (Shore A) or above.

The choices of components A and B are dependent on the modeling materialused. Component A needs to have good adhesion to the modeling materialused, and is preferred to be the modeling material itself. Examples ofcomponent A are: poly(lactic acid) (PLA),acrylonitrile-butadiene-styrene triblock polymers (ABS), polycarbonate(PC), polystyrene (PS), high impact polystyrene (HIPS), polycaprolactone(PCL), polyamide (PA) or Nylon, thermoplastic polyurethanes (TPUs),ethylene-vinyl acetate (EVA) copolymers, styrene-butadiene-styrene (SBS)and styrene-ethylene-butadiene-styrene (SEBS) copolymers, acrylic andacrylate polymers, methacrylic and methacrylate polymers, poly(methylmethacrylate) (PMMA), poly(butylene terephthalate) (PBT), poly(ethyleneterephthalate) (PET), polyethylene (PE), poly(ethylene oxide) (PEO),poly(hydroxybutyrate), styrenic polymers, poly(norbornene),polyoctenamer, poly(pentenamer), polypropylene (PP), poly(propyleneoxide) (PPO), polyurea, polyurethane urea, poly(vinyl acetate) (PVAc),poly(vinyl alcohol) (PVA or PVOH), poly(vinyl butyral) (PVB), poly(vinylchloride) (PVC), poly(vinyl fluoride), starch-based polymers,styrene-acrylonitrile copolymers, styrene-methylmethacrylate copolymers,siloxane polymers, cellulose-based polymers. Preferrably, component A isselected from commonly used modeling materials for FDM/FFF processes.Examples of commonly used modeling materials that can be used ascomponent A are: poly(lactic acid) (PLA),acrylonitrile-butadiene-styrene (ABS), polycarbonate (PC), polystyrene(PS), high impact polystyrene (HIPS), polycaprolactone (PCL), polyamide(PA) or Nylon, thermoplastic polyurethanes (TPUs).

Poly(lactic acid), which is sometimes abbreviated as “PLA” is a highlypreferred modeling material for use in conjunction with this invention.Poly(lactic acid) is a high molecular weight polyester which issynthesized by the polymerization of lactide monomer, which is a cyclicdimer of lactic acid, or 2-hydroxypropionic acid. Lactic acid is achiral molecule with two enantiomeric forms, l-lactic acid d-lacticacid. Typically l-lactic acid and d-lactic acid are both present in PLA.The PLA for the current invention is preferred to have an l-lactic acidcontent in the range of 85% to 100%. Examples of such PLA materials are2500HP, 4032D, 2003D, 4043D and 7001D from NatureWorks LLC.

The selection of component B is based on what is used as component A.Examples of suitable polymers for component B include: poly(lactic acid)(PLA), acrylonitril-butadiene-styrene (ABS), polycarbonate (PC),polystyrene (PS), high impact polystyrene (HIPS), polycaprolactone(PCL), polyamide (PA) or Nylon, thermoplastic polyurethanes (TPUs),ethylene-vinyl acetate (EVA) copolymers, styrene-butadiene-styrene (SBS)and styrene-ethylene-butadiene-styrene (SEBS) copolymers, acrylic andacrylate polymers, methacrylic and methacrylate polymers, poly(methylmethacrylate) (PMMA), poly(butylene terephthalate) (PBT), poly(ethyleneterephthalate) (PET), polyethylene (PE), poly(ethylene oxide) (PEO),poly(hydroxybutyrate), styrenic polymers, poly(norbornene),polyoctenamer, poly(pentenamer), polypropylene (PP), poly(propyleneoxide) (PPO), polyurea, polyurethane urea, poly(vinyl acetate) (PVAc),poly(vinyl alcohol) (PVA or PVOH), poly(vinyl butyral) (PVB), poly(vinylchloride) (PVC), poly(vinyl fluoride), starch-based polymers,styrene-acrylonitrile copolymers, styrene-methylmethacrylate copolymers,siloxane polymers, cellulose-based polymers.

In addition to components A and B, the support material disclosed inthis application can further contain other ingredients, such as, but notlimited to: other polymers, colorants, pigments, fillers, fibers,plasticizers, nucleating agents, heat/UV stabilizers, process aids,impact modifiers, and other additives.

The blending of components A and B and other ingredients can beconducted using various polymer mixing/compounding techniques such assolvent mixing, melt mixing, continuous mixing, etc. It is preferred toconduct mixing using an extrusion process with a single- or twin-screwextruder.

In order to be used in FDM/FFF processes, the material is oftenprocessed into a filament form, as this is the preferred form that isused in most current FDM/FFF equipment. The most commonly used processto convert the material into a filament form is melt extrusion. In themelt extrusion process, various ingredients, either pre-compounded orindividually added and dry-blended, are fed into a polymer extruder(either single-screw or twin-screw) with a cylindrical die andcontinuously extruded. The extrudate is subsequently quenched/cooled andpulled by a puller to give the desired physical dimensions before beingcollected. The process can also include equipment such as melt or gearpumps (to ensure a stable output), laser micrometers (on-linemeasurement of the physical dimensions), etc. The filament is preferredto have a uniform diameter with a circular cross section. The filamentcan be manufactured into almost any diameter. However the most commonlyused diameters for 3D printing are about 1.75 mm and 3 mm with filamentshaving a diameter which is within the range of 2.75 mm to 3.15 mm alsobeing frequently used. In any case, it is important for the diameter tohave a small variation, as large variations in diameter can lead to poorprinting quality and feeding problems. It is preferred for the filamentto have a variation of less than ±0.1 mm.

The filament should be reasonably straight in order to feed properlyinto the printing head. As straightness or kinkiness is difficult todefine, here we use a practical testing method to verify thestraightness. The method involves passing the filament through a ringgauge with an internal diameter of d_(F)+0.15 mm (d_(F) being theaverage filament diameter) and a thickness of 8.5 mm at a speed of about50 mm/min. If the filament has large kinks, it will not be able to passthe ring gauge. The test can be used as a quality assurance step for thefilament.

The disclosed support material can be used as a dedicated supportmaterial on dual-extruder FDM/FFF printers. It can also be used as forsingle-screw FDM/FFF printers. In the latter case, the support materialis used for both the printed part as well as support.

This invention is illustrated by the following examples that are merelyfor the purpose of illustration and are not to be regarded as limitingthe scope of the invention or the manner in which it can be practiced.Unless specifically indicated otherwise, parts and percentages are givenby weight.

Example 1

A poly(lactic acid) (PLA) (4043D from NatureWorks, LLC) and athermoplastic polyurethane (TPU) (Estane TPU S375D from Lubrizol) in themass ratio of PLA:TPU=25:75 were fed into a 20 mm single-screw extruderwith a cylindrical die with a diameter of 3 mm to manufacture a filamentwith a targeted diameter of 1.75 mm. The processing conditions are asfollows:

2 3 1 (compression (metering 4 Screw (feed zone) zone) zone) (die) (rpm)120° C. 190° C. 215° C. 190° C. 30

The manufactured filament exhibits an average diameter of 1.75 mm with<±0.05 mm in variation. The TPU has a phase-separated morphology, withTPU and PLA forming the continuous matrix and dispersed phase,respectively.

The produced material was heated and sandwiched between a glass slideand a cover slip for observation by optical microscopy. The micrographshowed that PLA forms spherical particles, with diameters ranging fromseveral microns to 20 microns, evenly dispersed in a continuous matrixof TPU.

Example 2

The manufactured filament as described in Example 1 was loaded onto adual-extruder desktop FDM/FFF 3D printer (Replicator 2X from MakerBotIndustries, LLC). Several models with large overhang portions were usedto test the support performance as well as the ease of support removal.The basic printing conditions are as follows:

-   -   Modeling material: PolyPlus™ PLA (manufactured by JF Polymers        (Suzhou) Co. Ltd.), printed at 195° C.    -   Support material: printed at 220° C.    -   Build plate temperature: 60° C.

The printing speed used was 90 mm/s. For all models tested, the supportstructure was adequate in supporting the overhang portions, and can beafterwards removed with simple pulling and tearing actions. In mostcases the support can be removed by hand or with simple tools such astweezers. No residue support material is visible on the printed model,meaning that the fracture always occurs at the support-model interface,as designed. In average it takes 1-2 minutes to remove all the supportstructure for the tested models.

Example 3

The manufactured filament as described in Example 1 was loaded onto asingle-extruder desktop FDM/FFF 3D printer (Up! Plus 2nd Generation fromBeijing Tier Times Technology Co., Ltd.). In this case the material isused both as the modeling material as well as the support material. Itwas found that, once a relatively large model infill density (>50%) isused, the support can be removed easily without breaking the model.

Variations in the present invention are possible in light of thedescription of it provided herein. While certain representativeembodiments and details have been shown for the purpose of illustratingthe subject invention, it will be apparent to those skilled in this artthat various changes and modifications can be made therein withoutdeparting from the scope of the subject invention. It is, therefore, tobe understood that changes can be made in the particular embodimentsdescribed which will be within the full intended scope of the inventionas defined by the following appended claims.

What is claimed is:
 1. In the process of manufacturing athree-dimensional article by additive manufacturing which includesextruding at least one modeling filament and at least one temporarysupport filament into a desired geometric shape, the improvement whichcomprises the temporary support filament having a diameter which iswithin the range of 1.65 mm to 1.85 mm or which is within the range of2.75 mm to 3.15 mm, wherein said temporary support filament is comprisedof a polymeric composition which is comprised of a first polymericcomponent which is suitable for use as a modeling material and a secondpolymeric component which is immiscible with the first polymericcomponent, wherein the polymeric composition has a continuous phase anda discontinuous phase, wherein the continuous phase is comprised of thesecond polymeric component, wherein the discontinuous phase is comprisedof the first polymeric component, wherein the first polymeric componentis present in the polymeric composition at a level of up to 40 percent,and wherein the polymeric composition has a Shore A hardness of at least80.
 2. The process as specified in claim 1 wherein the filament of thetemporary support material has a diameter which is within the range of1.65 mm to 1.85 mm.
 3. The process as specified in claim 1 wherein thefilament of the temporary support material has a diameter which iswithin the range of 2.75 mm to 3.15 mm.
 4. The process as specified inclaim 1 wherein the first polymeric component is selected from the groupconsisting of poly(lactic acid), acrylonitrile-butadiene-styrenetriblock polymers, polycarbonate, polystyrene, high impact polystyrene,polycaprolactone, polyamides, thermoplastic polyurethanes,ethylene-vinyl acetate copolymers, styrene-butadiene-styrene triblockpolymers, styrene-ethylene-butadiene-styrene copolymers, acrylicpolymers, acrylate polymers, methacrylic polymers, methacrylatepolymers, poly(methyl methacrylate), poly(butylene terephthalate),poly(ethylene terephthalate), polyethylene, poly(ethylene oxide),poly(hydroxybutyrate), styrenic polymers, poly(norbornene),polyoctenamer, poly(pentenamer), polypropylene, poly(propylene oxide),polyurea, polyurethane urea, poly(vinyl acetate), poly(vinyl alcohol),poly(vinyl butyral), poly(vinyl chloride), poly(vinyl fluoride),starch-based polymers, styrene-acrylonitrile copolymers,styrene-methylmethacrylate copolymers, siloxane polymers, andcellulose-based polymers; and wherein the second polymeric component isselected from the group consisting of poly(lactic acid),acrylonitrile-butadiene-styrene triblock polymers, polycarbonate,polystyrene, high impact polystyrene, polycaprolactone, polyamides,thermoplastic polyurethanes, ethylene-vinyl acetate copolymers,styrene-butadiene-styrene triblock polymers,styrene-ethylene-butadiene-styrene copolymers, acrylic polymers,acrylate polymers, methacrylic polymers, methacrylate polymers,poly(methyl methacrylate), poly(butylene terephthalate), poly(ethyleneterephthalate), polyethylene, poly(ethylene oxide),poly(hydroxybutyrate), styrenic polymers, poly(norbornene),polyoctenamer, poly(pentenamer), polypropylene, poly(propylene oxide),polyurea, polyurethane urea, poly(vinyl acetate), poly(vinyl alcohol),poly(vinyl butyral), poly(vinyl chloride), poly(vinyl fluoride),starch-based polymers, styrene-acrylonitrile copolymers,styrene-methylmethacrylate copolymers, siloxane polymers, andcellulose-based polymers.
 5. The process as specified in claim 4 whereinthe modeling filament is comprised of the same composition as is thefirst polymeric component.
 6. The process as specified in claim 1wherein the first polymeric component is poly(lactic acid), and whereinthe second polymeric component is a thermoplastic polyurethane.
 7. Theprocess as specified in claim 6 wherein the modeling filament iscomprised of poly(lactic acid).
 8. The polymeric composition asspecified in claim 1 wherein said polymeric composition has a Shore Ahardness of at least
 90. 9. The polymeric composition as specified inclaim 1 wherein said polymeric composition has a Shore A hardness of atleast
 95. 10. The polymeric composition as specified in claim 1 whereinsaid polymeric composition is further comprised of a colorant or apigment.
 11. The polymeric composition as specified in claim 1 whereinthe polymeric composition is not capable of absorbing more than 1 weightpercent water.
 12. The polymeric composition as specified in claim 1wherein the first polymeric component is poly(lactic acid).
 13. Thepolymeric composition as specified in claim 1 wherein the secondpolymeric component is a thermoplastic polyurethane.
 14. The polymericcomposition as specified in claim 1 wherein the poly(lactic acid) has anl-lactic acid content which is within the range of 85% to 94%.
 15. Thepolymeric composition as specified in claim 6 wherein the thermoplasticpolyurethane is present in the polymeric composition at a level which iswithin the range of about 60 weight percent to about 90 weight percent.16. The polymeric composition as specified in claim 6 wherein thepoly(lactic acid) is present in the polymeric composition at a levelwhich is within the range of about 15 weight percent to about 40 weightpercent and wherein the thermoplastic polyurethane is present in thepolymeric composition at a level which is within the range of about 60weight percent to about 85 weight percent.
 17. The polymeric compositionas specified in claim 6 wherein the poly(lactic acid) is present in thepolymeric composition at a level which is within the range of about 20weight percent to about 30 weight percent and wherein the thermoplasticpolyurethane is present in the polymeric composition at a level which iswithin the range of about 70 weight percent to about 80 weight percent.